The present invention relates to an endoscope apparatus, and more specifically to an endoscope apparatus with an insertion guide for assisting insertion of an insertion section of an endoscope into an object of inspection.
Endoscopes, especially industrial endoscopes, are used for the observation of various objects of inspection of different sizes. However, when inserting an insertion section of one such conventional endoscope into a duct with an inner diameter greater than the outer diameter of the distal end portion of the section, for example, the insertion section would stagger in the duct, failing to accurately fix the viewing direction. Moreover, the insertion section would be biased to the bottom side of the duct, thus permitting observation of only the bottom wall portion of the duct.
Thereupon, an endoscope with an insertion guide is disclosed in, e.g., Japanese Patent Disclosure No. 135820/81. The guide is mounted around the distal end portion of the insertion section, and assists it in being inserted into the object of inspection. The guide is fitted on the insertion section by screwing a threaded portion formed on the outer peripheral surface of the distal end portion of the section into another threaded portion formed on the inner peripheral surface of the guide, or by pressure-bonding part of the guide to part of the insertion section.
According to the screwing method, however, the engagement between the two threaded portions may become loose during use, so that the insertion guide may become disengaged from the insertion section. In the case of the bonding method, on the other hand, the guide requires a complicated clamping mechanism.